Total RNA from 92 invasive cervical cancers was analyzed for the presence of multidrug-resistance (MDR1) gene (also known as PGY1) transcripts. A 4.5-kilobase MDR1 transcript band was detected in 40 (43%) of 92 invasive cervical carcinomas and in 15 (68%) of 22 normal cervices. MDR1 levels were low [mean, 2.5 arbitrary units (U)] except in one liver metastasis (50 U) treated with a drug regimen including vincristine. Of eight carcinomas treated by radiotherapy and/or chemotherapy, seven (88%) exhibited MDR1 transcripts as compared with 24 (35%) of 69 untreated carcinomas (Fisher's exact test; P = .01). In conclusion, our data suggest that the MDR1 gene plays a role in drug resistance of certain cervical cancers, but also that other mechanisms may be involved.